/*  WinUSBNet library
 *  (C) 2010 Thomas Bleeker (www.madwizard.org)
 *  
 *  Licensed under the MIT license, see license.txt or:
 *  http://www.opensource.org/licenses/mit-license.php
 */

using System;
using System.Threading;
namespace MadWizard.WinUSBNet
{
    internal class USBAsyncResult : IAsyncResult, IDisposable
    {
        private readonly AsyncCallback _userCallback;
        private bool _completed;
        private bool _completedSynchronously;
        private ManualResetEvent _waitEvent;
        private int _bytesTransfered;
        private Exception _error;

        public USBAsyncResult(AsyncCallback userCallback, object stateObject)
        {
            AsyncState = stateObject;
            _userCallback = userCallback;
            _completedSynchronously = false;
            _completed = false;
            _waitEvent = null;
        }

        public object AsyncState { get; }

        public Exception Error
        {
            get
            {
                lock (this)
                {
                    return _error;
                }
            }
        }
        public int BytesTransfered
        {
            get { return _bytesTransfered; }
        }
        public WaitHandle AsyncWaitHandle
        {
            get
            {
                lock (this)
                {
                    if (_waitEvent == null)
                    {
                        _waitEvent = new ManualResetEvent(_completed);
                    }
                }
                return _waitEvent;
            }
        }

        public bool CompletedSynchronously
        {
            get
            {
                lock (this)
                {
                    return _completedSynchronously;
                }
            }
        }

        public bool IsCompleted
        {
            get
            {
                lock (this)
                {
                    return _completed;
                }
            }
        }

        public void Dispose()
        {
            Dispose(true);
            GC.SuppressFinalize(this);
        }

        public void OnCompletion(bool completedSynchronously, Exception error, int bytesTransfered, bool synchronousCallback)
        {
            lock (this)
            {
                _completedSynchronously = completedSynchronously;
                _completed = true;
                _error = error;
                _bytesTransfered = bytesTransfered;
                _waitEvent?.Set();
            }
            if (_userCallback != null)
            {
                if (synchronousCallback)
                {
                    RunCallback(null);
                }
                else
                {
                    ThreadPool.QueueUserWorkItem(RunCallback);
                }
            }
        }
        private void RunCallback(object state)
        {
            _userCallback(this);
        }
        protected virtual void Dispose(bool disposing)
        {
            if (disposing)
            {
                // Cleanup managed resources
                lock (this)
                {
                    _waitEvent?.Close();
                }
            }
        }
    }
}